Field of the Invention
The present invention relates generally to a brushless motor, and more particularly to a brushless motor having a rotating shaft provided with a leadscrew and a gear.
Description of the Related Art
A variety of apparatuses or optical apparatuses, such as a camera and an interchangeable lens, includes a small motor, such as a stepping motor, a coreless motor, and an inner rotor magnet type brushless motor.
Japanese Patent Laid-Open No. (“JP”) 2010-016923 discloses a stepping motor that includes a rotor that has a leadscrew (output section) attached rotating shaft and a magnet, and a stator that has a coil and a stator core enclosing the coil and disposed around the magnet. A frame configured to hold a bearing that rotatably supports an end of the rotating shaft on the output section side is fixed onto one end surface of the stator core in its axial direction. The end of the rotating axis on the magnet side is rotatably supported by a bearing held between the other end surface of the stator core in the axial direction and a metal plate (end plate) fixed onto the stator core. A flat spring is attached to the frame, and configured to force the end of the rotating shaft on the output section side toward the end on the magnet side.
JP 2003-333818 discloses an inner rotor magnet type brushless motor in which a stator having a coil and yoke is located around a rotor magnet of an inner rotor that has a rotating shaft with a tip to which an output member, such as a gear, can be attached. The rotating shaft is rotatably supported by the bearing held by a tip flange and a distal flange. The tip flange is attached to the tip of a case configured to cover an outer circumferential surface of the stator, and the distal flange is attached to the distal end of the case in the axial direction. This motor has a small diameter part located at one end of the rotor magnet in the axial direction, and smaller than that of another part, and includes a Hall element disposed between the small diameter part and the inner circumferential surface of the coil. The Hall element is mounted on a Hall element substrate disposed between the rotor magnet and the distal flange in the axial direction.
The leadscrew attached rotating shaft and the frame configured to support it disclosed in JP 2010-016923 are applicable to the brushless motor disclosed in JP 2003-333818. However, when the frame disclosed in JP 2010-016923 is simply fixed onto the tip flange of the motor of JP 2003-333818, the motor overall length including the frame in the axial direction increases. In addition, it is necessary to improve the assembly precision of the entire motor, such as positioning precisions of the rotor having the output section attached rotating shaft and the stator.